The Iwate Koen Park, also known as Morioka Castle Ruins Park, is the historic remains of Morioka Castle that was built in 1663 as the castle for the feudal lord of the Nanbu Domain. The stone walls made of Morioka granite remain even today, and for its beauty this castle is counted as one of the three famous castles of Tohoku. The figure of the stone walls has been preserved along with the poem inscriptions of Morioka-born Miyazawa Kenji and tanka inscriptions of Ishikawa Takuboku. The scenery around the castle changes with the seasons, allowing visitors to enjoy not only the history of the region, but also the cherry blossoms, plum groves, and wisteria flowers of spring, the hydrangeas of summer, and the changing colors of autumn.